LM7909 Pinout, Equivalent, Features, Applications, and More

 LM7909 Description

LM7909 is a negative voltage regulator IC of the LM79XX series that provides accurate and stable -09V output, there are also other negative voltage regulators in this series which are LM7905, LM7906, LM7908, LM7909, LM7910, LM7912, LM7915, LM7918 and LM7924. All the ICs in this series are available in the TO-220 package and have 3 output pins which are Input, Output and Ground. The IC also has many features like thermal overload protection, safe area protection, short circuit protection etc. All these features make this IC robust and reliable for commercial equipment and also for experimental projects of students and tinkerers.

Moreover, the IC requires only one component at the output which is a capacitor that stabilizes the output voltage. The input capacitor is only necessary if the IC is more than 3 inches far from the input supply filter capacitor. If the input and output capacitors values are more than 100uf then two protection diodes should be used to protect the IC from capacitors output spikes to protect the IC’s internal circuitry from damaging.

LM7909 IC Features / Technical Specifications

1. TO-220 Package
2. Up to 1.5A output current (Some manufacturers also make in 1A output current)
3. Short circuit protection circuitry
4. Overheat shutdown circuitry
5. Low price
6. Reliable for commercial use
7. Stable -09V output
8. Maximum input voltage is 35V DC
9. Low quiescent current

Where & How to Use

LM7909 can be used in a variety of power supplies, Charger circuits, and voltage converter circuits. To get stable -09V at the output the input must be -2V to -3V higher than the output. A suitable heatsink will be required with the IC. Using the IC is pretty straightforward; it will be connected to the negative supply of the load.

Applications

1. Dual power supply circuits
2. Voltage step-down circuits
3. Battery charger circuits
4. Solar power supply circuits 
5. Motor drivers circuits
6. Power Supply Applications: Providing a stable -9V power supply for various electronic components and circuits.
7. Audio Circuits: Supplying a negative voltage bias for audio amplifiers or certain audio processing stages.
8. Bipolar Power Supply Configurations: Creating a bipolar power supply by using the LM7909 alongside a positive voltage regulator to generate both positive and negative voltages.
9. Biasing Circuits: Using the LM7909 in biasing circuits to set reference voltages for specific applications, such as operational amplifier configurations.

Replacement and Equivalent

UA7909, GL7909, KIA7909P if LM7909 is not available then you can also use LM337 adjustable negative voltage regulator IC and set it to -09V fixed output.

Important Note:

As technology evolves, newer and more efficient voltage regulators may become available, so it's always a good idea to check for the latest options and improvements in voltage regulation. Always refer to the datasheet and application notes provided by the manufacturer for proper usage and design considerations.

Datasheet

To download the datasheet just copy and paste the below link in your browser.

https://cdn.datasheetspdf.com/pdf-down/L/M/7/LM7905_NationalSemiconductor.pdf